Clear a preference when sync tries to delete a preference

chrome/browser/prefs/prefs_syncable_service_unittest.cc

Index: chrome/browser/prefs/prefs_syncable_service_unittest.cc
diff --git a/chrome/browser/prefs/prefs_syncable_service_unittest.cc b/chrome/browser/prefs/prefs_syncable_service_unittest.cc
index e9650eec8d8f0a5b8ed1c1380711a42ceba3a6ae..e5d06a7a15b670cdec4bc50937f03a2f16d3636e 100644
--- a/chrome/browser/prefs/prefs_syncable_service_unittest.cc
+++ b/chrome/browser/prefs/prefs_syncable_service_unittest.cc
@@ -693,7 +693,7 @@ TEST_F(PrefsSyncableServiceTest, DynamicManagedDefaultPreferences) {
   // Switch kHomePage to managed and set a different value.
   base::StringValue managed_value("http://example.com/managed");
   GetTestingPrefService()->SetManagedPref(prefs::kHomePage,
-                                                    managed_value.DeepCopy());
+                                          managed_value.DeepCopy());
   // The pref value should be the one dictated by policy.
   EXPECT_TRUE(managed_value.Equals(&GetPreferenceValue(prefs::kHomePage)));
   EXPECT_FALSE(pref->IsDefaultValue());
@@ -706,3 +706,19 @@ TEST_F(PrefsSyncableServiceTest, DynamicManagedDefaultPreferences) {
   // There should still be no synced value.
   EXPECT_FALSE(FindValue(prefs::kHomePage, out).get());
 }
+
+TEST_F(PrefsSyncableServiceTest, DeletePreference) {
+  prefs_.SetString(prefs::kHomePage, kExampleUrl0);
+  const PrefService::Preference* pref =
+      prefs_.FindPreference(prefs::kHomePage);
+  EXPECT_FALSE(pref->IsDefaultValue());
+
+  InitWithNoSyncData();
+
+  scoped_ptr<base::Value> null_value(base::Value::CreateNullValue());
+  syncer::SyncChangeList list;
+  list.push_back(MakeRemoteChange(
+      1, prefs::kHomePage, *null_value, SyncChange::ACTION_DELETE));
+  pref_sync_service_->ProcessSyncChanges(FROM_HERE, list);
+  EXPECT_TRUE(pref->IsDefaultValue());
+}